The prior art discloses various animal collars which are described as releasing a substance over a period of time onto the body of an animal. The material released is generally either a vapor emitted from a solid material or a powder dispensed from a particular collar structure. Collars for dispensing a powder necessarily utilize some form of compartment for holding the powder to be dispensed. U.S. Pat. Nos. 254,156; 2,342,066; 2,349,713; 2,401,253; 2,734,483; and 3,904,746 disclose examples of powder dispensing animal collars.
The prior art devices, however, do not controllably emit an amount of powder which effectively covers the animal as provided by the present invention. Further, the prior art devices do not emit an effective amount of powdered material over substantially the entire body surface of the animal for a predetermined extended period of time as provided by the present invention.
Additionally, and--we think--most importantly, the prior art does not disclose a thermoformed collar which provides for the controlled emission of a powdered material over an extended period of time using a plurality of pores in the collar wall as encompassed by the present invention.